Re: data corrupting bug in 2.4.20 ext3, data=journal

[Nick Piggin]

Andrew Morton wrote:

>Nick Piggin wrote:
>> 
>> Andrew Morton wrote:
>> 
>> >In 2.4.20-pre5 an optimisation was made to the ext3 fsync function
>> >which can very easily cause file data corruption at unmount time.  This
>> >was first reported by Nick Piggin on November 29th (one day after 2.4.20 was
>> >released, and three months after the bug was merged.  Unfortunate timing)
>> >
>> In fact it was reported on lkml on 18th July IIRC before 2.4.19 was
>> released if that is any help to you. 2.4.19 and 2.4.20 are affected
>> and I haven't tested previous releases. I was going to re-report it
>> sometime, but Alan brought it to light just the other day.
>> 
>
>Are you sure?  I can't make it happen on 2.4.19.  And disabling the new
>BH_Freed logic (which went into 2.4.20-pre5) makes it go away.
>
>
>--- linux-akpm/fs/jbd/commit.c~a	Sun Dec  1 23:10:12 2002
>+++ linux-akpm-akpm/fs/jbd/commit.c	Sun Dec  1 23:10:27 2002
>@@ -695,7 +695,7 @@ skip_commit: /* The journal should be un
> 		 * use in a different page. */
> 		if (__buffer_state(bh, Freed)) {
> 			clear_bit(BH_Freed, &bh->b_state);
>-			clear_bit(BH_JBDDirty, &bh->b_state);
>+//			clear_bit(BH_JBDDirty, &bh->b_state);
> 		}
> 			
> 		if (buffer_jdirty(bh)) {
>
I reported the bug for 2.4.19-rc1 and 2 but I can't remember if I tested 
2.4.19
when it was released. It has an external journal on a seperate disk. I can't
really do any testing with the machine unfortunately.

Regards,
Nick